Telephone system



Aug 18, I925. 1,550,300

G. A. YANOCHOWSKI TELEPHONE SYSTEM Filed May 15'. 1919 s Sheet-Sheet 1 E50! E17 azmr'iwwski Aug. 18,1925. 1,550,300

. G. A. YANOCHOWSKi TELEPHONE SYSTEM Filed May 15. 1919 n 3 Sheets-Sheet 2 Aug. 1a, 1925. 1,550,300

G. A. YANOCHOWSKI TELEPHONE SYSTEM Filed May 15. 1919 3 Sheets-Sheet 5 22717277575 Eeurgefi/azwcfiawsh' station of the system being supplied w Patented Aug. 13, 1925.

GEORGE A. YANoonowsKI, or CHICAGO. rumors, nssie'uon ToKnLi-oee SWITCH- BOARD AND SUIILY COMPANY, G2? QHTZGItGQ,

ILLINOIS.

TELEPHONE Applicationfiled may 15,

To all whom it may concern:

Be it known that I, Gnome A. Yancorrows-Kr, a citizen of the United States of America; residing: at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Telephone Systems, of which the following is a specification.

ltl'y invention relates to telephone systems and has to do more particularly with systems of the so-called switching type in which impulses transn'iitted from a calling line by a subscriber thereat actuate switches to seek the contacts of a line which is being called. The system which is herein di. closed is applicable to private automatic eX- change systemsand is con'unonly known in the art as a P. A. X.. system. it syst i i of this kind is adapted to serve a plurality cit stations, say twenty-two in nu' br single motion rotary switch such as is dis closed in a patent to" Harry H. lde, issued Oct. 21, 1924, No. 1,512,101. An object of my invention is the provision of an improved circuit arrangement which embodies desirable features and advantages all in an eflicient, simple and economical manner.

A feature of my invention is the provision of means whereby trunlr connections with a main exchange may be allotted to certain stations to the exclusion of. others, and means whereby an idle trunk is automatically seized. The above features as well as others will be more fully hereinafter described. 7

The novel features of the invention through the provision of which the above mentioned and other advantageoi'i's results a 'e attain-ed will be? explained by referring to the accompanying. drawingsin which like reference characters in the several views denote like parts,' and in which Fig; 1 illustrates diagrammatically a private automatic exchange including the circuit of my invention Fig. 2, which includes parts 1: and Q, i'llus trates the circuit of my invention operating in connection with a trunl arrangement whereby connection may be obtained with a main exchange.

Referring now in general to Figure 1,1 show acalling substatiolr A: connected to an individual: switch circuit 13.: The calling trainee-s, A oo'nronn'rron or SYSTEM.

19%. Serial No. 297,247.

substation A comprises the usual substation apparatus and in addition, a calling device CD and a grounding key GK for purposes as will presently be described. The indi vidual switch B comprises line i'elays LR and LR, a switching relay SW and a motor magnet MM. Off-normal contacts ON are also provided and assume their alternate position upon the first step of the switch off normal. A; guard relay and a slow acting ren S also provided for'putposes as will be more particularly pointed out in the following specifications The switch B may be similar to the switch illustrated and described inconnection with a patent to Harry H. lde. o'. l 51.2,1;01 issued Oct. 21, 1924.

The switch i'salso provided with wipers and 5, which are ad pted to engage cont etc 6.7, 8 and 9 The wipers 3, 4', and the private and line wipers operative-- i associated with the private and line conry wiper 2' and T 8 and 9. The aux 6 are used for trunking purposes be more fully hereinafter described. To the right of the drawing, 1 show a called substation C (similar to the calling? substation-A) tQlJlTllllZlillDQ in a; line switch B',si1ni lar to the line switch B.

Having described in general the appara tus ofFigure 1, I will now describe in detail the circuit connections which may be established between the calling subscriber at substation A and the called subscriber at substation C. The subscriber at the substa ti'on A in initiating a cal'l,'. removes his receiver from the switch hook to close an: 611 ergizing circuit for the line relays LR and LR traced from battery through the wind ing of the relay LR. conductor 10;: through the now closed contacts of the substation switchho'ok back through the winding of the line relay LE to ground, the two relays LR' and LR operating in seriesii 'lhe desg ing" of alternate contact 11 oitline relay LR establishes an energizing circuit for the relay S from battery, through the winding of the said relay bl; over conductor 12' to ground at alternate Contact 111' of line relay LR.

Assuming further that the callednumber of the called subscriber 15', tl1e subscriber at'tlie substation A now actuates his calling device. to send fifteen impulses of current',.

the subscriber"mtuatingthe dial CD by pulling the naught digit and then by pulling the digit live, which will transmit fifteen 1mpulses of current to the switch B. These impulses of current bring about fifteen de energiza-tions and energizations of the line relays LR and LR and upon the first deenergization of th line relay LR, a circuit is established for the motor magnet MM, traced from battery at normal contact 13 of the guard relay GR, conductor 14, through the winding of the motor magnet MM, conductor 15, alternate contact 16 of relay S, conductor 17 to ground at normal contact 18 of relay LR. The magnet MM is thus energized and tie-energized 15 times, the motor magnet stepping the wipers 2, 3, a and 5 into engagement with the contacts 6, 7, 8 and 9, which contacts lead to the called subscriber of substation C. The energization and de-energization of line relay LR is only incidental at this time. The relay S does not (lo-energize during the rapid interruptions of alternate contact 11 of line relay LR, due to its slow-release construction. Upon the first step of the switch wipers off normal, the off-normal contacts ON assume their alternate position and the closing of alternate contacts 53 of oft-normal contacts ON places a ground on the private normals 58 of the calling substation A, thus preventing any other subscriber from seizing the contacts of the calling line. The subscriber A having selected th contacts of the wanted cal ed line, depresses the key GK to impress ringing current upon the called line to signal substation C. Assuming that substation C is idle, key GK opens the series ener zing circuit of the line relays LR and LR, and LR restores, but th relay LB remains energized over a circuit traced from battery, through the relay, conductor 10, to ground at alternate contact 19 of the hey GK. The private contact 7 being idle and relay LR having restored while the key GK is do pressed, a series circuit is established for the guard relay GB of the switch circuit 13, and the switching relay SW of the switch B, traced from battery through the winding of the guard relay GR, conductor 20, normal contact 21, conductor 22, normal contact 23, conductor 2%, contact 7, wiper arm 3, conductor 25, the upper winding of the switch relay SW conductor 26, norinal contact 2. of line relay LR, conductors 23 and 29, to ground at alternate contact of line relay LR. The switching relay SlV upon energization closes its alternate cortact 31, establishing a locking circuit for itself, traced from battery through the lower winding of the said relay, alternate contact 31, conductor 29, to ground at alternate contact 30 of relay Ll The closing ct alternate contact 32 of switching relay SW extends the ground from alternate contact 30 of line relay LR over conductor 29 to alterna-te contact 32, and then over conductor 25 to the wiper arm 3 and private contact 7, placing a ground or busy potential upon the contact 7, preventing any other calling subscriber from engaging the contacts of the called substation C, and the ground placed upon the private contact 7 also maintains relay GR energized over conductor 24, normal contact 23, conductor 22, normal contact 21, conductor 20, through the winding of relay GR to battery. The closing of alternate contact 33 of the switching relay SlV connects the ringing generator Gr and ringing current is impressed upon the called line, said ringing current being traced from the ungrounded pole of generator G, through alternate cont-act 33, conductor 34-, normal contact 35 of relay LR, alternate contact 36 of relay SW, wiper arm 5, contact 9, through condenser and call bell to the called substation C, back through contact 8, wiper arm 41, alternate contact 37 to ground at norm-a contact 38 relay LR. Each time the key GK is depressed, ringing current is connected to the called line. The subscriber at the substation O in response to the signal, removes his receiver from the substation switch hook, closing an energizing circuit for the line relays LR and LE of the switch B from battery, through the winding of relay LR conductor 39, through the now closed contact of the substation swicch hook, back through the winding of relay LE to ground. The closing 01 alternate contact 40 of line relay LR establishes an energizing circuit for the relay S from battery through the winding of relay S, conductor ell, to ground at alternate contact 0 of relay LE The closing of alternate contact 42 of the relay S establishes a locking circuit for the guard relay GR, trared from battery, through the wind ing of relay GR, alternate contact 43, conductor ll to ground at alternate contact 4-2 of relay S. The subscriber at the calling substation A and the called substation C are now in conversational circuit, said circuit being traced over the heavily .iarked conductors, said conductors having the condensers I: and K interposed.

Assuming now that the subscribers have finished conversation, they replace their receivers upon their respective switch books. The replacing oi: the receiver at the calling substation A opens the series energizing circuit of the line relay LR and line relay LR, and the opening of alternate contact 11 of line relay LR opens the energizing circuit of the relay S. The closing of normal contact 45 of relay S upon its deenergization establishes an energizing circuit for the motor magnet MM traced from ground at the now normal contact 45, conductor l6, alternate contact 47 of the offnormal spring contacts ON which assume ill ma'l contact of motor magnet MM, conductor I-l, to battery and ground at normal contact 13 of relay GB. The motor magnet MM; is' thus ei-orgized and tie-energized due to. the opening and closing of its normal contact 4:9, and upon the last step of the wipers back to their normal position, the off-non inal contacts ON are again engaged to be moved back to their normal position, and the. opening of alternate contact 4i? opens the circuit of motormagnet Mh l preventing its; turther actuation. The replacing oi the receiver of the called substation C opens the energizing circuit for the line relays LE and LR, and the opening of alternate contact 10 of line relay LE opens the energizing circuit oi the relay S. The relay S upon restoring to normal opens its alternate contact 42 to open the locking circuit for the relay GR, The apparatus used for establishing connection between the calling subs ation- A and the called substation C are new at normal and available for establishing other connections.

Assi-uning now that the subscriber at the called substation C is busy, the operation of the circuit is the same up to and including the time that the calling subscriber at the substation A depresses the key GK. The subscriber C being busy, its private con- 7 will have a ground or busy potential upon it from its grounded contact of its oii normal contact, if it is a calling line, or from the ground through the alternate conaco of a switching relay SlV, if it is a called line. Upon the depression of the key GK at the calling substation A no current flow is established through the switching relay ST? as the circuit through the upper winding of the said relay SlV will extend from ground at alternate contact 30 of relay LR, conductors 29 and 28, normal contact 2? of relay LR, which relay de-energizes upon the actuation of the key GK, conductor 26 through the, winding of the relay W, conductor 25, wiper arm 3 to ground at the busy contact 7. The relay SW failing to energize, a busy back signal is transmitted to the calling substation A, traced from the busy bac r apparatus BB, normal contact 50 of relay SW conductor 51, alternate contact 52 ot the oil-normal contacts ON, through the substation back through the line relay LE to ground. The subscriber is thus notified that the called line is busy and replaces his receiver upon the switch hook, thus bringing about the de-energization of the line relays LR and LR and of the relay S. The closing of normal contact 45 of relay S again establishes a circuit for the motor magnet MM, as previously described, stepping the wipers 2,3, 4 and 5 back to their normal position, and upon the last step of the wipers, the o'fi-normal contacts ON assume their normal position and the appara-tus is now at normal and available for establishing other connections.

Referring now to 2, parts 1 and 2, I ilir trate a calling subscriber as D termiir ng at the private automatic exchange into an individual switch B similar to that of ll. The subscriber at l) ma establish local calls between subscribers at the private branch exchange, and may also be provided withtrunk service. The switch B associated with the calling substation D has its last three contacts connected with trunk lines leading to the main exchange. These contacts are not necessarily mu tipled througi all the other switches, but are engaged by the wiper 2- which engages successive contacts 6 to seek an idle trunk'lead ing to the main exchange.

neei erring to F 2, part 1, the substation l) contains the usual substation apparatus,

in a amn is also supplied with a calldevice CD and key GT The switch in a line circuit L, which comprises the line rclzy Tilt, the cut-oil relay CO, multiple line sin-nails LS and multiple jacks J. In addhro-n I show a trunk relay TR and a coil P for purposes as will be more fully hereinafter described.

The line circuit L as illustrated is'lmown as a multiple line lamp circuit in which a line lamp as LS is provided or each line J so that when a trunkis seized by a station at the private autor; atic e1;- e, a lighted line lamp LS appears before each 01 a plurality of operators at the main e:-;change, any one of whom ma 7 seize the call to the exclusion of the others.

Fig. 2, part 2, illustrates an operators cord circuit M themain exchange and comprises an answering plug AP and a calling plug CP. The answering end of the cord circuit M comprises an answering tip supervisory relay AT and an answering sleeve supervisory relay AS. The answering sleeve supervisory relay AS upon energization connects the op ators set U to the cord conductors. A high resistance test re- TE. is also provided which prevents more than one operator seizing the same call. A link disconnect relay Ll) is also provided which actuatcs upon the termination of conversation to disassociate the connected line circuit E1 from the cord circuit M, as will be more fully hereinafter described. The link circuit M is adapted to be used to interconnect ordinary manual lines such as line E. The special tone feature is of particular use when such connections are established.

The callingv end of the cord circuit is provided with a sleeve relay SR which relay ling actuates when the calling plug CP is inserted into the jack of a called line. A ringing control relay RC and aringing interrupter relay RT are also provided, the ringing relay Bl periodically interrupting the ringing current and the ringing control relay LC controlling the application of ringing current. A party line ringing key BK is also provided for connecting ringing current to the called line. it calling supervisory relay CT is also provided wuich actuates upon the response of the called sub scriber. The line circuit L associated with the called line E comprises the usual line relay LR multiple line lamps LS, multiple jacks J, and the cut-oil relay CO.

Assuming now that the subscriber at the substation D of the private automatic exchange initiates a call and wishes to be connected to one of the trunks leading to the main exchange. The switch 13 which is a twenty-live point switch, will have the last three contacts arranged for trunking purposes. The first two contacts of the last three lead to the main exchange and terminate in line circuits as L. The last contact of the three is on open circuit, for purposes as will be more fully hereinafter described. Assuming that the trunk line is designated by the numeral the subscriber at substation l) wishing a trunlr connection, removes his receiver to bring about the operation of line relays LE and LE and relay S as previously described, and now actuates his calling device to send twe ty-three impulses of current, and the wipers are stepped into engagement with contacts 6, 7, S and 9 which are the twenty-third These contacts are connected to the first trunk leading to the main exchange. Should the said trunl: be busy, there will be a ground or busy potential upon the auxiliary contact 6 from ground at alternate contact 60 of a switching relay Sil to the other switch that is already ei'igaging the contacts 7, 8 and S). This ground upon the auxiliary contact 6 closes an energizing circuit for the motor magnet M traced ii in i cry, through normal contact 61 of relay conductor 63, through the winding of motor m gnet MM its normal contact (is, normal contact 60 of the relay Si l conductor 65, wiper arm 2 to the grounded contact (3. The magnet MM upon energization steps the wipers 2, 3, l and 5 into engagement with the next set of contacts, and assuming that it is idle, no ground or busy potential will be on it and therefore no energizing circuit for motor magnet M3? is established. The said wip rs remain in engagement with the said engaged contacts 6, 7, 8 and 9.

The subscriber at the substation B now actuates hey GK to bring about the deenergization of the line relay on ing an energizing circuit for relay TR of the line circuit L traced from battery,

through the winding of said relay TR, conductor (56, contact 7, wiper arm 8, conductor 67, through the upper winding of the switching relay SW conductor 68, normal contact (39 of relay LE conductors and 71 to ground at alternate contact 72 of relay LB". The switching relay SlV closes a locking circuit for itself, as previously described, and places a busy potential upon auxiliary contacts 6 to prevent any other subscriber from seizing the trunk no occupied by the subscriber D. Relay S also places a busy potential upon the private contact 7 through its alternate contact, the said ground also holding relay TR energized, as previously described. The relay Tit upon energization closes its alternate con act '73, establishing an energizing circuit for the line relay LR of line circuit ll traced from battery, through the winding of the said relay LE normal contact 7-l relay Ci), alternate contact 73 of relay TR, through the winding of the coil P to ground at normal contact 75 of relay CO. The line relay LR energizing closes its alternate contact 76 to light the multiple line lamp signals LS which appear before ditlerent operators positions. One of a plurality of operators seizes the call by insorting the answering plug AP into the multiple acli J of the trunk T, closing an energizing circuit for the high resistance test circuit- TE, traced from battery, through the winding of the said relay TE, conducter 77, normal contact 78, sleeve contacts of the connected plug AP and jack J through the winding of relay CO to ground. Relay at this time does not energize \Jk/ due to the high resistance of relay TE. The closing of alternate contact 79 of the test relay TE establishes an energizing circuit for the answering sleeve supervisory relay traced from battery through the winding of said relay AS, alternate contact 79, conductor 77, normal contact 78, sleeve con tacts of the connected plug AP and jack J, through the winding of relay CO to g 'ound. Relay G0 now energizes to open its normal contact 7 1-, allowing the said line relay 1 to de-energize and open the circuit of the multiple line lamps LS. The clay AS upon energization closes its alternate contact 80, which establishes a locking circuit for itself, traced from battery, through the winding of said relay AS, its alternate contact 80, conductor 81, and thence over conductor 77, normal contact 78, sleero contacts of the plug AP and jack J to ground through the winding of the cutoff relay CO. The relay AS is thus held energized ini'lependent of the contact 79 of the high resistance test relay TE. Should thus clos-a second operator attempt to answer the llt call, the low resistance relay AS of the first cord prevents the high resistance test relay TE from operating due to the shunting effect of relay AS of the first cord, and this being the case, the second operator will receive a special tone notifying her that the call has been seized by another operat r, and she therefore reino es the answering plug from the multiple pick of the seized line upon receiving the tone,

The special tone is traced from the special tone apparatus ST, through the winding of relay AS of the cord circuit M which we have assumed has seizedthe call which is to lee-extended from the privateexchange, alternate contact '80 of the answering supervisory relay AS, conductors 81 and 77, nor mal contact 78 of relay LD, sleevecontacts of the connected plug AP of cord circuit M, and jack J of line circuit L, the circuit then extends from the said sleeve of the jack J to the sleeve ofthe multiple jack as 5 into which the second operator has inserted a plug AP,the sleeve contacts of the answering plug AP of the second cord, normal contact 78 of the relay 'LD of-the second cord, conductor 77, normal contact-79 oi the high resistancetest relay TE of the second cord, which relay TE fails-to energize as already described,normal contact of relay AS of the second cord, conductor 80 through the winding 87 01: the operators set associated with the second connected cord to ground. The operator of the cord circuit M having seized the call, her op erators set 0 is connectedto the conductors of cord circuit M, traced over conductorsSS and 89, alternate contacts 90 and 91 of the'answering supervisory relay AS, conductors 02 and 98, normalcontacts 94 and 95 of relay SR and over conductors 96 and 97 to the 'tip and sleeve cord conductors. The supervisory relay AT is also energized upon the insertion of the answering plug Al into'the jack J, the circuit being traced from battery, through the lower winding of answering tip supervisory relay AT, conductor 98, normal contact 052 of link disconnect relay Ll), ring contacts ofthe connected plug AP and acl; J, alternate contact 73 of relay Tlt, through the winding of coil l tip contacts of the connected plug AP and jack J, normal contact 100 of relay Ll), and through the upper winding of the supervisory relay AT to ground. The opening of normal contact 101 of relay AT prevents the premature glowing of the answering supervisory lamp AL.

The operator being thus connected, now inquires the wants of the --calling substation D at the private exchange, and assuming that it is the subscriber at the substation 15 that is wanted, the operator of the cord circuit E tests the multiple jack J? of the called line as to its idle or busy condition in the usual manner and if it is busy, she receives the customary busy click in her head receiver. Assuming that the called subscriber at substation l0 is idle, the operator now inserts the calling plug Cl into the multiple jack J of the called line, thus closing a circu? tor the sleeve relay SR of the cord circuit M and the cut-oil relay C0 of the line circuit L into which the called line Eterniinates, from battery, through the winding of the sleeve relay SR, sleeve contacts of the connected plug UP and jacl; J to ground, through the winding of therelay C0. The supervisory relay SR upon energization opens its normal contacts 94; and 95 to disconnect the operators set 0 from the cord c0; ductors and the closing cl alternate con tact 100 of the said relay SR closes a circuit for the calling supervisory lamp CL,

traced from battery, through the lamp CL,

normal contact- 107 of the ringing control relay ltC, conductor 108, normal contact 109 of relay UT, conductors 110 and to ground at alternate contact 106 of relay fill.

The calling supervisory lamp CL thus remains lighted until the ringing key is depressed to signal the ca led for subscriber at substation To signal the called for subscriber at the substation E, one of tie plurality ott' ringing hey plungers 0t rin ing key BK is depressed to connect the prop er frequency of ringing current upon the called line to actuate the call signal at the substation E of the called subscriber. 'lhe depression of one of the ringing key plungers of the ringing hey BK also brings about the momentary actuation of a set oi end springs of the said ringing hey lllti. The closure of alternate contact 108 or the end springs closes an ener aing circuit for the ringing control relay oil, traced from battery, through the winding of the said ringing control relay RC, conductor 102, through the momentarily closed contact 103 of the end springs of the ringing hey BK, conductor 104:, conductor 105 to ground at alternate contact 106 of the sl eve relay SR. The opening oil normal contact 107 of ringing control relay RU opens the circuit for the calling supervisory lamp CL the etlaceinent oi which lamp signifies to the operator that the called party wanted is being signalet. The closing ofthe alternate contact 107 the ringing control relay RC also establishes a locking circuit for it elf, traced :trombattery,through the winding of the said ring ing control relay its alternate contact 107, conductor 108, normal contact 100 of the calling supervisory relay CT, conductor 11.0, conductor 105 to ground at alternate rotating interrupter I, through the winding of the ringing interrupter relay RT, conductor 112, through alternate contact 111 of ringing control relay RU, conductor 113, normal contact 103 of the end springs of ringing key BK, which springs restore when the ringing key plunger assumes its ringing or indicating position, conductors 10st and 105 to ground at alternate contact 106 of sleeve relay SR. Due to the constantly rotating interrupter I, the relay R1 is thus intermittently energized and de-energized and ringing current is thus applied intermittently to the call bell at the called substation E. The ringing current is traced from the ungrounded pole of the ringing generator G which we will assume is the proper gen erator frequency, alternate contact 11atli depressed ringing key plunger of the ringing key BK, ringing conductor 115, alternate contact 116 of ringing interrupter relay RI, when in one of its energized positions, conductor 117, alternate contact- 118 of sleeve relay SR, tip contacts 01 the connected calling plug Cl and jack 5, through the call bell and condenser of the called substation E and back through the ring con tacts oi" the connected plug C and jack J conductor 119 to battery and ground at al ternate contact 120 of the ringing interrupter relay RT. The call bell of the subscriber at the called substation E is thus intermittently rung, due to the intermittent energization and de-energization of the ringing interrupter relay The removal oi the receiver at the called substation E in response to the call signal, closes an energizing circuit for the calling supervisory relay CT, traced irom battery, through the lower winding of the said calling supervisory relay, normal contact 121 or" the ringing interrupter relay -31, when the said relay is in one of its de-energized positions, conductor 122, ring contacts of the plug GP and jack J, through the now closed switch hook contacts at the substation E, back through the tip contacts of the connected plug CP and ,jack J, alternate contact 118 of sleeve relay SB, conductor 11?, normal contact 116 of the ringing interrupter relay R1 and through the upper winding of the supervisory relay T to ground. The relay CT, upon cnergization, opens the locking circuit of ringing control relay RC, at its normal contact and the relay RC opens the energizing circuit of ringing interrupter relay RT its alternate contact 111 and the relay E1 upon restoring to normal opens its alternate contact 116, preventing further application of ringing current. The subscriber at the private ex change station D and the subscriber at the main exchange called substation E are now in conversational circuit, the said talking circuit being traced over the heavily marked conductors. Assuming that conversation has terminated, the subscribers at the stations D and E replace their receivers upon their respective switch hooks and the replacing of the receiver at the called substation E interrupts the circuit at the calling supervisory relay CT at the switch hook contacts and the closing of normal contact 109 of relay CT closes an energizing circuit for the calling supervisory lamp CL, traced from battery, through the lamp CL, normal contact 107 of relay RC, conductor 108, normal contact 100 01 relay CT, conductors 110 and to ground at alternate contact 106 of relay SE. The calling supervisory lamp CL is thus lighted and notifies the operator that the called subscriber has replaced his receiver. The subscriber at the branch exchange substation D replacing his receiver upon its switch hook opens the energizing circuit for the line relays LE and LB and the line relay LR restoring opens the energizing circuit or" the slow-acting relay S The opening of alternate contact oi relay LR opens the energizing circuit for switching relay SW and the said relay restoring, removes the ground or busy potential on the private contacts 7, and the closing of normal contact of relay S closes an energizing circuit for the motor magnet MM and the motor magnet M11 then steps the wipers 2, 3, 2i and 5 to their normal position, and when the wipers reach normal, oil-normal contacts 0N are restored, opening the circuit of motor magnet MM This restoration of switch B is the same as described in connection with Fig. 1 and a detailed description is not deemed necessary. The ground having been removed from private contact 7 upon the restoration of relay S11 the energizing circuit for the rely TB of the trunk T is interrupted and the relay TR restoring, its contact 73 assumes its normal position which opens the energizing circuit of answering supervisory relay AT, which relay restores, and the closing of it's normal contact 101 establishes an energizing circuit for the link disconnect relay LD, traced from battery, through the winding of the relay LD, conductor 130, normal contact 101 01. relay AT, conductor 131, alternate contact 132 of relay AS, conductors 104 and 105 to ground at alternate contact 106 of relay SR. The closing of normal contact 101 also establishes a circuit for the answering supervisory lamp AL from battery, through the said lamp, normal contact 101, conductor 131,211- ternate contact 132, conductors 104 and 105 to ground at alternate contact 106, the said lamp lighting and notifying the operator that the subscriber at the branch exchange has replaced his receiver. The relay LD upon energization opens its normal contacts 99 and 100, disassociating the line circuit L from the cord conductors, and the opening of normal contact 78 of relay LD opens the circuit for relay AS and the relay CO, but relay AS remains energized through alternate contact 183 of relay LD, normal contact 101 of relay AT, its alternate contact 132 to ground at alternate contact 106. The relay C0 of circuit L now restores and should the operator at the main exchange leave the plug in the jack after the subscribers have finished conversation, the trunk used in establishing the connection just described is not rendered useless for as soon as the subscriber at the private exchange replaces his receiver, the trunk is cleared, due to the energization of relay Ll) of the cord circuit and the trunk is thus immediately available and should the trunk last used be again seized, the line relay LR will again energize, due to the restoration of relay CO and the ener -ization of relay LR will again light the multiple line signals LS so that the call may be again seized by the same operator or another operator. The same operator seizing the call, removes the calling plug OP from the jack, allowing rclay SR to restore, and the relay SR restoring, connects the operators set O to the cord conductors. When the operator notes the two lights, supervisory signals All and CL and knows that conversation has terminated, she removes theplugs AP and GP from their respective jacks J and J. This removal of the plug OP allows relay SE to restore, and the relay SR restoring opens the circuits of relays LD and AS a-nd'signals AL and CL. The apparatus which was used in establishing a connection is now at normal and available for establishing other connections.

To prevent certain stations at the private exchange from connecting with contacts which will connect them with the main exchange, the last three contacts, which we assumed are for trunking purposes of their associated switches, are not connected as illustrated, but are left open. Now, when a subscriber, who is not allotted trunlr service, tries to seize a trunk contact by calling the trunk number, the wiper 3 of his switch engages the trunk contact but as it is in open circuit, the switching relay SW of the said switch remains at normal and thus receives a busy signal from the busy back apparatus BB, and hearing it, he replaces his receiver, thus allowing the switch to restore to normal, as previously described.

Connectors that operate as do those herein described to add together all the digits transmitted that operatively affect the connector, may be concisely referred to as adding-type connectors.

While I have illustrated my invention operating in connection with a preferred circuit arrangement, I do not wish to be limited to the same as it is applicable with other arrangements, and changes modifications will also suggest themselves to those skilled and I, therefore, aim to cover all such changes and modifications as come within the spirit and scope oi the appended claims.

What I claim as new; and desire to secure by United States Letters Patent, is:

l. A telephone system including an auto matic switch having a driving magnet for advancing and restoring the same, a line terminating in multiple jacks via said switch, multiple line lamps for said line adapted to glow responsive to the removal of the receiver at the substation on said line,

(Mia.

common battery cord circuits or connection under the control of the subscriber for connecting the subscribers line to said trunk, a cord circuit provided with a plug for connection to said trunk, and means cont-rolled by the disconnection of said subscribers line from said trunk to cause said cord circuit to be operativcly disconnected from said trunk, said switch being also adapted to operate to connect the subscriber thereat to at subscribers line exclusively oi said trunk circuit and said cord circuit.

3. A telephone system including subscribers telephone lines, adding-type connector switch individual thereto provided with a single level olbank contacts, other subscribers lines terminating in said bank contacts, and trunk lines leading to a main exchange terminating in said bank contacts, subscriber-controlled means for electing the V first one of said trunk line automatic means for thereafter selecting an idle one of said trunk lines, and operators cord circuits for extending calls from said trunk lines to called subscribers lines.

t. A telephone system including a subscribers telephone line, a switch individual thereto, other subscribers telephone lines terminating in the bank of said switch, an automatic switch for one of said other lines, a cut-oil relay for said last switch, means controlled by the said first subscriber for energizing said cut-oil relay, means controlled by the response of the other of said subscribers for removing the 'controlof said cut-oil relay from said first subscriber and opera placing it entirely under the control of said second subscriber, the releasing of said switch remaining under the control of said first subscriber.

A telephone system including a subscribers line, an automatic switch individual thereto provided with a level of banl: contacts, part of said bank contacts terminating in other subscribers lines, and the rest of the bank contacts terminating in trunk circuits, automatic means individual to said switch for selecting an idle one of said iliU3li circuits and operable to cause the wipers of said switch to rotate to the bank contacts oi the last trunk line it the preceding trunl lines ire busy, means whereby said switcl r test the idle or busy tes to tllQlGllftG condition of said last trunk line, and operators cord circuits for connecting to idle trunl; lines to extend a call therefrom to a called subscribers line.

G. A telephone system including trunks, subscribers lines, selectors individual to said lines for automatically picking out idle ones of said trunks, other trunks adapted for connection with the first to extend calls toward called lines, and means for operating the selectors to free the first trunks for use in other connections while said first trunks still remain connected with terminals of the said other trunks, said selectors also adapted to operate to interconnect siid sub scribers lines exclusively of said first and said other trunks.

7. In combination with adding-type connectors, said connectors ope able in a single plane and adapted to automatically restore to normal after termination of conversation,

ephono circuits adapted to be automatically selected by said connectors, said add ing-type connectors also adapted to connect to each other in conversational circuit exclrsi said telephone circuits, only a \ely or pair of said connectors being required to eittect a conversational circuit between two subscribers, and audible busy-back means i indicating when a called for subscriber is busy.

8. ln combination wth adding-type connectors, said connectors operable in a single plane and adapted to automatically restore to normal after termination of conversation, means for operating them to select idle trunks, other manually operated trunks adapted to be linked with those first mentioned, teri'uinal therefor adapted to be connected to su scribers lines, automatic means in said other trunks controlled by the calling subscribers for freeing said addingt e connectors from said other trunks, and audible busy-back means for indicating when a called for subscriber is busy.

9. A telephone system including manually equipped lines and automatically equipped lines, adding-hype connectors for operation over the two sides of the automatically equipped lines in series, trunks provided *ith manually operated terminals associated with the manually equipped lines, said c0n nectors having also automatic devices for selecting idle trunks.

10. A telephone system including telephone lines, adding-type connectors controlled ovcr the two sides of the said lines in series for operation to establish connections with some or" said lines, automatic secircuits for the connectors and busy trunl-is to be selected, and connective means applying the latter to others 01 said lines.

ll. A telephone system including a tele phone line, pair of electromagnets in series therewith, means for simultaneously vibrating them by digit impulses, a relay controlled by the one maintaining its arma' ture in operated position while said magnets vibrate, circuit connections tor holding the first magnet in operated position while the second retracts its armature, a test relay switched into circuit responsive to said magnets, a source of ringing current connected in when said relay is in one operative position, a source of busy current connected in when said relay is in another operative condition.

12. In combination a telephone line, a pair of electromagnets in series therewith, means for vibrating them by digit impulses, while a third magnet maintains its armature in operated position, circuit connections for holding the first in operated position while the second retracts its armature, a test relay switched responsive to said magnets, a called line, a test relay for said line in circuit with said first relay, a source of current connected to said circuit and energizing both. said relays when the called line is idle.

A telephone system including a call ing and a called telephone line, a connector :tor each line operable over the two sides of the line in series, said connectors having each a test relay in temporary circuit with each other, calling line means comprising a pair of quick rel ase relays in series with said line for connecting a current source to said circuit, ringing means for said connector and means controlled by the calling subscriber for operating aid quick release relays for applying ri; ng current to said called line.

let. A connector having a pair of relays simultaneously vibrated by digit impulses, substation means to energize one while deenergizing the other, travel controlling means sensitive to the simultaneous vibra tions, and test controlling means sensitive to the second relation.

15. In combination a calling and a called line, each having a connector operable in a single plane over the two sides of the line in series, said connectors-operable in a single planetemporari ly switched together, a double wound test relay i'o one con ector adapted to -energize in series with a relay otth-e otherwvhen the called line is idle, an oil-normal contact of one connector only in said energizing'circuit and a pair of Si another when the called 'line is idle, an oil" normal contact of one connectoronly in said clr-cuit, and ringing and'b'usy bacx means controlled by said circuit, the apphcaton of ringing current to said'called line-being controlledunanually by the calling subscriber;

17. A" telephone system including telephone lines, connector, a contact serving to place a busy potential on the private normal of said connector, a digit-impulse vibrated relay having an armature contact to connect with a wiper of said connector to test the called line, a test relay with a winding in series between said contact andsaid wiper, and operating in a manner dependent on theelectrical condition of an engaged called line contact for switching a connection to said wiper to render the called line busy.

18.- An automatic exchange including a pair of relays adapted to be simultaneously vibrated in series with the two limbs of a line, a called line, and a test relay forcsaid connector to test the called line having a test winding controlled jointly by s-aidyre lays and a locking winding for said test relay.

19. An automatic exchange including a relay adapted to be operated over the two limbs of the line in series to advance a gle level connector switch and over one over one limb at the will of the subscriber for another purpose, another relay operated I over said line, a test relay for said connector,

and circuit meansso-lely'controlled by said hmb at the willof the subscriber, for an,

relays for coimectingsaidtest relay to one side of battery.- 1

21. A connector for automatic exchanges including a relay adapted to be operated over the two limbs oi the line or overone limb at the will cit I the subscriber, second relay operating in series with the first, a test relay for said connector, an armature contact of said first relay ioneer-1- trolling said test relay, armature means colitrolled by the second for switching said test relay, said contact and saidmeans solely controlling the conn'ection from one side of battery through said test relay-to the testwiper.

2'2. ,AQCOHHGCJEOI for automatic exchanges including a pair of relays adapted to be si multaneously digitally vibrated over the two limbs oi the line, ates-trelay-fo'r said connector, and acircuittherefor including contacts of both said relays.

23. A connector for automatic exchanges including a pair of relays adapted to be simultaneously digitally vibrated" over the line, a test-relay for said connector, and a circuit therefor effective for testing purposes when closed through a back contact-0f one of said first-mentioned relays, and a front contact of the other;

24. A. telephone system including a test relay, an energizing circuit and aghol-ding circuit. for said relay, a 'pair-of relaysin series with the line and simultaneouslyvibrating their armatures in response to digit impulses, contacts of bothqrelays of'said 1 pair inv one of said circuits,-anda contact of one relay of said pair only in the other of said circuits.

25. A telephone system including an automatic switch havinga driving magnetfor advancing and restoring thesame, a Slibf scriberis line terminating in multiple line lamps via said automatic-switch, means for causing said multiple line lamps to glow responsive to the removal of the receiver at the substation, common battery cord circuits for answering calls from the subscribers substation, means for preventingthe eliective connection of more than oneof said cord circuits tosaid subscribers .line when attempting to vanswer a call, audible means for apprising an operator of onecord circuit when the operator of another cord circuit has efi'ectively connected to the subscribers' line, and automatic disconnect means 'for disassociating the cord circuit efiectively connected to said calling line from said. calling line. H

26. A telephone systemincluding an au tomatic switchhaving a driving magnet for advancing and restoring thesame, a sub scribers line terminating in multiple line lamps, via said automatic switch, means for causing saidmultiple line lamps to glow. r pens t th emoval'of the m n st the substation, common battery cord circuits provided with automatic listening for answering calls from the subscriberssubstation, means for preventing the effective connection of more than one or said cord circuits to said subscribers line when attempting to answer a call, audible means for apprising an operator of one cord circuit when the operator of another cord circuit has effectively connected to the subscribers line, and automatic disconnect means for disassociating the cord circuit eilectively connected to said calling line from said calling line.

27. A telephone system including an auto ,matic switch having a driving magnet for advancing and restoring the same, a sul scribers line terminating in multiple line lamps, via said automatic switch, means for causing said multiple line lamps to glow responsive to the removal of the receiver at the substation, common battery cord circuits for answering calls from the subscribers substation, means for preventing the effective connection of more than one of said cord circuits to said subscribers line wien attempting to answer a call, audible means for apprising an operator of one cord circuit when the operator of another cord circuit has effectively connected to the subscribers line, and automatic disconnect means for said cord circuit for disassociating said cord circuit effectively connected to said subscribers line from said subscribers line.

28. A telephone system including an automatic switch having a driving magnet for advancing and restoring the same, a subscribers line terminating in multiple line lamps via said automatic switch, means for causing said multiple line lamps to glow responsive to the removal of the receiver at the substation, common battery cord circuits for answering calls from the subscribers substation, means for preventing the effective connection of more than one of said cord circuits to said subscribers line when attempting to answer a call, audible means for apprising an operator of one cord circuit when the operator of another. cord circuit has edectively connected to the subscribers line, and automatic intermittent ringing means for said cord circuits for signaling called subscribers.

v 29. A telephone system including an automatic line switch having a driving mag net for advancing and restoring the same, a subscribers line terminating in multiple line lamps via said automatic line switch, means for causing said multiple line lamps to glow responsive to the removal of the receiver at the substation, common battery cord circuits for answering calls from the subscribers substation, said cord circuits being provided with automatic listening, automatic disconnect and automatic ringing,

means for preventing the effective connection of more than one of said cord circuits to said subscribers line when attempting to answer a call, and audible means for apprising an operator of one cord circuit when the operator of another cord circuit has effectively connected to the subscribers line.

30. A telephone system including an automatic line switch having a driving magnet for advancing and restoring the same, a subscribers line terminating in multiple line lamps viasaid automatic line switch, means for causing said multiple line lamps to glow responsive to the removal of the receiver at the substation, common battery cord circuits for answering calls from the subscribers substation, means for preventing the effective connection of more than one of said cord circuits to said subscribers line when attempting to answer a call, audible means for apprising an operator of one cord circuit when the operator of another cord circuit has effectively connected to the subscribers line, and means whereby when the calling subscriber replaces his receiver may again immediately remove the same and relight multiple lamps to make a recall prior to the disconnection of the plug of the cord circuit from a called line.

31. A telephone system including a subscribers line, a switch individual thereto and provided with a driving magnet for ad vancing and restoring said switch, a trunk terminating in multiple acks and multiple line lamps before a plurality of operators, subscriber-controlled means for operating said switch to connect said subscribers line to said multiple jacks, thereby causing the glowing of the multiple line lamps, a plurality of operators cord circuits "for answering the call, means for preventing the cll ective connection of more than one of said cord circuits to said subscribers line in answering the call, and audible means tor notifying operators connecting to said subscribers line subsequently to said effective connection that the call has been seized by another operator.

32. A telephone system including a subscribers line, a switch individual thereto and provided with a driving magnet for advancing and restoring said switch, a truul: terminating in multiple jacks and multiple line lamps before a plurality of operators, subscriber-controlled means for operating said switch to connect said subscribers line to said multiple jacks, thereby causing the glowing of the multiple line lamps, a plurality of operators cord circuits for answering the call, means for preventing the effective connection of more than one of said cord circuits to said subscribers line in answering the call, aut matic audible means for notifying the operators connecting to said subscribers line subsequently to the ill scribers line, a switch individual thereto and provided with a driving magnet tor advancing and restoring said switch, a trunk termi ating in multiple and multiple line-lamps before a plurality of operators, subscribercontrol;ed means for operating said :switch to connect said subscribcus line to ,said multiple jacks, thereby causing the glowing of the multiple line lamps, a alui of operators cord circuits for ansu' ring-the call, means for preventing the eii ective connection of more than one off said cord circuits to said subscribei"s line in answeringthe call, automatic audible means for notifying the operators connecting to said subscribefis line subsequently to the effective connection of said first operator and said line thatthe call has been seized by another operator, and a aromatic disconnect means under the control or the subscriber for freeing the .cord circuit from the trunk .circ tit and for disconnecting the subscribers linest'roin the trinilr-circuits.

,34. A telephone ystem including a subscribers line, a switch individualthereto and provided with a driving magne 1- advancing and restoring said switch, a tru iterminating in multiple jacks and multiple line lamps before a plurality of operators, subscriber-controlled means tor ope 'ating said switch to connect said subscribers line to said multiple jac-lrs, thereby causing the glowing of the multiple line lamps, aphirality of olerators cord circuits for ansr Fling the call, means for preventing the iive .connectionpot more than one of said cord circuits to said suhscrib-efis line in answearing the call, automatic audible means for notifying the operators connecting to said subscribers line subsequently to the effective connection of said first operator and said line that the call has been seized by another operator, and automatic listening means for said cord circuits.

telephonesystem includinga subscribers line, a switch individual thereto and provided with a driving; magnet for advancing and restoring said switch, a trunk terminating in multiple jacks and multiple line lamps before a plurality of operators, subscriher-controlled means tor operating said switch to connect said subscribers line to said multiple jacks, thereby causing the glowing of the multiple line lamps, a plurality of operators cord circuits for answering the call, means for preventing the eliiective connection of more than one of said cord circuit to said subscribers liue in answering the call, automatic audible means for notifying the operators connecting-to said subscribers lino subsequently to the eiiective connection oiv said first operator and said line that the call has been seized by another operator, and automatic ringing for said corn circuits.

86. A telephone system including ,a subscribers line, a switch individual thereto and provided with driving magnet for ad vane?n;- and restoring said switch, a trunk terminating in multiple jacks and multiple line lamps before a plurality of ope. subscriber-controlled 21 ans for operating said s vitch to connect said subscril ers line to said multiple jacks, thereby causingthe glowing of the multiple line lamps, a plurality of operators cord circuits tor answering the call, means for prevei 1,5; the ciieetive coimeclion of more than one of said cord circuits to said subscribers line in answering the call, and means includingan audible tone device for apprising one operator when the other operator has eiiectively connected to the suhscfbers line.

37. A telephone system including a subscribers line, a switch individualthereto 1 i rality of operators,

said cord circuits to said subscribefis line in answe'ing the call, whereby said subscriber may recall prior to the disconnection of the cord circuit from the trunk circuit, and automatic audible means for n 'titying the operator at the second cord circuit connected to said line that another cord circuit has been connected to said'line prior to said second cord circuit.

38. A telephone system including a subscribers line, a switch individual thereto and provided with a driving magnet for advancing and restoring said switch, a trunlr terminating in multiple jacks and multiple line lamps before a plur'lity of operators, subscriber-controlled means for operating said switch to connect said subscribcrs line to said multiple jaclrs, thereby causing the glowing oi the multiple line lamps, a plurality of operators cord circuits foranswering the call,-means for pre venting the etiective connection of? more than one of said cord circuits to said subscribers line in answering the call, where by the trunk circuit may again be used prior to the removal ot the plug of the cord circuit from the ack of the trunk circuit, and

automatic audible means for notifying the operator at the second cord circuit con nected to said line that another cord circuit has been connected to said line prior to said second cord circuit.

39. A semi-automatic telephone system including an automatic switch provided with means for progressively advancing and re storing the same. a subscribers line terminating in multiple line lamps via said automatic switch, means for causing said multiple line lamps to glo responsive to the removal of the receiver at the substation, common battery cord circuits for answering calls from the subscribers sul station, means for preventing the effective connection of more than one of said co'd circuits to said subscribers line when attempting to answer a call, a signal for apprising an operator of one cord circuit it the operator at another cord circuit has effectively connected to the subscribers line, and automatic disconnect means whereby the subscriber may operatively disconnect his line "from the cord circuit connected thereto.

40. semi-auton'iatic telephone system including an automatic switch provided with means for progressively advancing and restoring the same, a subscribers line terminating in multiple line lamps via said automatic switch, means for causing said multiple line lamps to glow responsive to the removal of the receiver at the substation, common battery cord circuits provided with automatic listening for answering calls from the subscribers substation, means for preventing the ell'ective connection of more than one of said cord circuits to said subscribers line when attempting to answer a call, signal for apprisii g an operator of one cord circuit it the operator at another cord circuit has eilectively connected to the sub scrihers line, and automatic disconnect means whereby the subscriber may operatively disconnect his line from the cord circuit connected thereto.

ll. A semi-automatic telephone system ineluding an automatic switch provided with means for progressively advancing and restori g the same, a subscribers line terminating in multiple line lamps via said automatic switch, mean for causing said multiole line lamps to glow responsive to the removal of the receiver at the substation, common battery cord circuits for answering calls from the subscribers substation, means for preventing the cliective connec ion of more than one of said cord circuits to said subscribefis line when attempting to answer a call, a signal for apprising an operator of one cord circuit it the operatorat another cord circuit has eti'ectively connected to the subscribefis line, and automatic disconnect means whereby the subscriber may operatively disconnect his line from the cord circuit connected thereto.

42. A semi-automatic telephone system including an automatic switch provided with means for progressively advancing and restoring the same, a subscribers line termiating in multiple line lamps via said automatic switch, means for causing said multiple line lamps to glow responsive to the removal of the receiver at the substation, common battery cord circuits for answering calls from the subscribers substation, means for preventing the effective connection of more than one of said cord circuits to said subscribers line when attempting to answer a call, a signal for apprising an operator at one cord circuit whether or not the operator at another cord circuit has effectively connected to the subscribers line, means controllable by the operator for automatically intermittently ringing said called subscriber, and automatic means controllable by the calling subscriber for operatively disconnecting his line from the cord circuit operatively connected to his line.

$23. A semi-automatic telephone system including an automatic switch provided with means for progressively advancing and restoring the same, a subscribers line terminating in multiple line lamps via said automatic switch, means for causing said multiple line lamps to glow responsive to the removal of the receiver at the substation, common battery cord circuits provided with automatic listening for answering calls from the subscfibers substation, means for preventing the effective connection of more than one of said cord circuits to said subscribers line when attempting to answer a call, a signal for apprising an operator at one cord circuit whether or not the operator at another cord circuit has eliectively connected to the subscribers line, means controllable by the operator for automatically intermitt ntly ringing said called subscriber, and automatic means controllable by the calling subscriber tor operatively disconnecting his line from the cord circuit operatively connected to his line.

A semiautomatic telephone system including an automatic switch provided with means for progressively advancing and restoring the same, a subscribers line terminating in multiple line lamps via said automatic switch, means for causing said multiple line lamps to glow responsive to the re moval of the receiver at the substation, common battery cord circuits for answering calls from the subscribers substation, means for preventing the effective connection of more than one of aid cord circuits to said subscribers line when attempting to answer a call, a signal for apprising an operator at one cord circuit whether or not the 013-,

connecting his line from the cord circuit operatively connected to his line.-

il semi-automatic telephone system in'cluding'a sabs'c ibers line terminating in in triple li'ncdanips m s'for'causing said multiple line lamps to glow responsive to the removal of the receiver at the substation; COHHDOHdQZLt-iely cord circuits for; an-

swering calls from the subscribers substation, means for preventing the etlective connection of more than one of said cord circuits to said subse-r ibers line when attempting to answer a call, asignal for apprising an operator at one cord circuit when the operator at another cord circuit has effectively connected to the calling subscribers line, a calling supervisory signal for the cord circuit effectively connected to the calling line, automatic means for intermittently signaling the subscriber on said called line, operator controlled means for effecting an operation oi said signaling means and for actuating said supervisory signal, means controlled by the called subscriber for dis connecting the signaling means from said called line, and automatic disconnect means controllable by the calling subscriber for operatively disconnecting his line from said cord circuit whereby he may initiate arecall prior to a disconnection of the answering plug of the cord circuit from the calling subscribers line.

46. A semi-automatic telephone system including a subscribers line terminating in multiple line lamps, means for causing said multiple line lamps to glow responsive to the removal of the receiver at the substation, common battery cord circuits provided with automatic listening for answering calls "from the subscribers substation, means for preventing the effective connection of more than one of said cord circuits to said subscribers line when attempting to answer a call, a signal for apprising an operator at one cord circuit when the operator at another cord circuit has elfectively connected to the calling subscribers line, a calling supervisory signal for the cord circuit etfeetively connected to the calling line, automatic means for intermittently signaling the subscriber on said called line, operator controlled means for effecting an operation of said signaling means and for actuating said supervisory signal, means controlled by the. called subscriber for disconnecting the signaling means from said called line, and automatic disconnect means controllable by the calling subscriber tor operatively disconnecting his line from said cord circuit whereby he may initiate a recall prior to a disconnection of the answering plug of the cord circuit from the calling subscribers line.

4:7. A semi-auton'iatic telephone system including a subscribers line terminating in tiple linelamps means for causing said nnilt'iple line is glow responsive to the removal of t. receiver at thesubstation,'con'imon battery cord circuits for answering ca is from the subscribers substation, means for preventing the elleetiveconnection of more than one of said cord circuits to said subscribers line when attempt ing to answer a call,-a signal for apprising an operator at one cord circuit when the operator at another cord circuit has e'tlectively connected to the callingsubscribers line, a calling supervisory signal for the cord circuit effectively connected to the calling line, automatic means for intermittently signaling the subscriber on said called line, operator controlled means for effecting an operation of said signaling means and for actuating said supervisory signal, means controlled by the calledsubscriber for dis connecting the signaling means from said called line, and automatic disconnect means controllable by the calling subscriber tor operatively disconnecting his line from said cord circuit whereby he may initiate a recall prior to a disconnection of the answering plug of the cord circuit from the calling subscribers line.

48. A semi-automatic telephone system including a subscribers line terminating in multiple line lamps, means for causing said multiple line lamps to glow responsive to the removal of the receiver at the substation, common battery cord circuits for answering calls from the subscribers substation, means for preventing the effective connection of more thanone of said cord circuits to said subscribers line when attempting to answer a call, an operators telephone, automatic means for connecting and disconnecting said operators telephone and one of said cord circuits, a signal for apprising an operator of one cord circuit it the operator of another cord circuit has eff ctively connected to the calling subscribers line, a called subscribefis lino, signal for the cord circuit effectively connected to the calling subscribcrs line operable when the cord circuit is connected to the called subscribers line, automatic ringing means, operator controlled means for connecting said automatic ringing means to said called subscribers line and for eftacing said supervisory signal, and automatic disconnect means controllable by i one of said subscribers for freeing said subscribefis line from said cord circuit prior to the removal of a plug of said cord circuit from a jack of said line.

A semi-automatic telephone system including a subscribers line terminating in multiple line lamps, means for causing said multiple line lamps to glow responsive to the removal of the receiver at the substation, common battery cord circuits for an swering calls from the subscribers substation, means for preventing the effective connection of more than one of said cord cir- 0 its to said subscribers line when attempting to answer a call, an operators telephone, automatic means for connecting and disconnecting said operators telephone and one of said cord circuits, a signal for apprising an operator of one cord circuit if the operator of another cord circuit has effectively connected to the calling subscribers line, a called subscribers line, a

signal for the cord circuit eiiectively connected to the calling subscribers line operable when the cord circuit is connected to the called subscribers line, automatic ringing means, operator controlled means for connecting said automatic ringing means to said called subscribers line and for efl'acing said supervisory signal, and automatic disconnect means controllable by one of said subscribers for freeing said subscribers line from said cord circuit prior to the removal of a plug of said cord circuit from a jack of said line.

Signed by me at Chicago, county of Cook and State of Illinois, this 13 day of May, 1919.

GEORGE A, YANOGI-IOVSKI. 

